RCA Spectra 70 - Page 107

Special Function # 5
Store Interval Timer
(SIT)
General Description
I Code
Privileged
Instructions
• This Special Function stores the current contents of the Interval Timer
into a memory halfword. The address of the halfword to receive the
contents
of the Interval Timer is indicated by the contents of the memory
location addressed by the address field of the Function Call instruction.
This instruction has no effect upon the Interval Timer.
• 03.
Format Base
Displacement
Condition Code
Interrupt
Action
o 3 4
• Unchanged.
•
Address Error.
Power Failure.
Machine Check.
Paging Error.
Paging Queue.
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Note • 1. If either this Special Function or the timer halfword addresses are
not on halfword boundaries, an Addressing Error Interrupt condi-
tion occurs.
2. Use of the Interval Timer and Diagnostic Snapshot by programs
may not occur together, since the counter register is common to both.
If the Diagnose function is initiated while the Interval Timer is
running, the shared counter is cleared to zero without occurrence
of the Interval Timer Interrupt and the Diagnose function assumes
control
of the counter. If the function being diagnosed is the Load
Interval Timer, the actual loading of the counter is inhibited but
the E. O. Flow is Diagnosed.
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